Help Identify LSD

So I went to check out a "YS1 LSD" trans, and upon looking in the axle hole, I seen something odd. I've never seen a LSD like this before, but the guy swears it's an OEM LSD. Maybe the early cable trans had these?
you can see through to the other side, although it's through a small hole, rather than being able to see through a hole the same size as the splined axle holes. I've never seen anything like it. I'm hoping it's not some cheapie OBX crap.

an update, it's out of the trans and you can get a better look at it. pay no attention to the chipped tooth on the final drive, i'm only looking to use the LSD. also the hole in the last picture, you cant see much though it, what you see in the picture is about all you can see up close. there's stuff blocking the view.